With blistering speed, underrated wrestling, and crushing power, Melvin Guillard is one of the most feared lightweights in mixed martial arts today, and for good reason. But if “The Young Assassin” has had an Achilles Heel, it’s been the submission defense that has faltered in losses to Joe Lauzon and Jim Miller. Guillard has vowed that he has sewed up that hole in his game, but there’s no way to test that better than in the Octagon, and that’s where Fabricio Camoes comes in. A jiu-jitsu black belt with seven tap out finishes, the Brazilian standout will prove whether Guillard is ready for life on the mat again.